使用PowerShell 5.1调用Invoke-RestMethod更新Azure DevOps变量组变量遇阻

环境 #

• PowerShell 5.1
• Azure DevOps Server 2020

问题描述 #

使用PowerShell 5.1的Invoke-RestMethod操作Azure DevOps库变量组：

• GET请求可正常获取变量组内容；
• 执行PUT请求时，最初无报错但变量未更新，仅返回类似GET请求的结果；后续触发Content-Type不支持错误，提示PUT方法仅接受application/json或application/json-patch+json类型。

错误信息 #

Invoke-RestMethod : {"$id":"1","innerException":null,"message":"The request indicated a Content-Type of \"\" for method type \"PUT\" 
which is not supported. Valid content types for this method are: application/json, 
application/json-patch+json.","typeName":"Microsoft.VisualStudio.Services.WebApi.VssRequestContentTypeNotSupportedException, 
Microsoft.VisualStudio.Services.WebApi","typeKey":"VssRequestContentTypeNotSupportedException","errorCode":0,"eventId":3000}
At C:\Users\user1\Documents\WIP Update Password Library Group Variables.ps1:19 char:16
+ ...  $results = Invoke-RestMethod -Uri $uri -Credential $credential -Body ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
    + FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

原代码 #

function Main{
    SetVariable
}

function GetVariables {
    $uri = 'my azure devops uri'
    $credential = SetCredentials -userId 'user1' -password 'P@$$w0rd123'
    $results = Invoke-RestMethod -Uri $uri -Credential $credential
    $results.value.variables
}

function SetVariable {
    $uri = 'my azure devops uri'
    $credential = SetCredentials -userId 'user1' -password 'P@$$w0rd123'

    $body = @{ aVariableInGroup = 'hello world'}

    $results = Invoke-RestMethod -Uri $uri -Credential $credential -Body  $body -Method Put
    $results
}

function SetCredentials ($userId, $password) {
    $securePassword = ConvertTo-SecureString -String $password -AsPlainText -Force
    return New-Object -TypeName PSCredential -ArgumentList $userId, $securePassword
}

Main

解决方法 #

问题根源 #

1. 未指定Content-Type：原PUT请求未设置-ContentType参数，导致请求头Content-Type为空，不符合Azure DevOps API要求；
2. 请求体格式错误：Azure DevOps变量组的PUT API需要提交完整的变量组对象，而非单个键值对；若仅需更新单个变量，使用PATCH方法更高效。

方案1：使用PUT方法（完整更新变量组） #

先获取当前变量组的完整数据，修改目标变量后再提交PUT请求：

function SetVariable {
    # 确保URI指向具体变量组，格式示例：http://server:8080/tfs/Collection/Project/_apis/distributedtask/variablegroups/{groupId}?api-version=6.0
    $uri = 'my azure devops uri'
    $credential = SetCredentials -userId 'user1' -password 'P@$$w0rd123'

    # 获取当前变量组完整数据
    $currentVarGroup = Invoke-RestMethod -Uri $uri -Credential $credential
    # 修改目标变量的值
    $currentVarGroup.variables.aVariableInGroup.value = 'hello world'
    # 转换为JSON字符串（需指定-Depth避免嵌套截断）
    $body = $currentVarGroup | ConvertTo-Json -Depth 10

    # 发送PUT请求，指定Content-Type为application/json
    $results = Invoke-RestMethod -Uri $uri -Credential $credential -Body $body -Method Put -ContentType 'application/json'
    $results
}

方案2：使用PATCH方法（部分更新变量） #

通过JSON Patch格式仅提交需要修改的变量，更高效：

function SetVariable {
    $uri = 'my azure devops uri'
    $credential = SetCredentials -userId 'user1' -password 'P@$$w0rd123'

    # 构造JSON Patch请求体，指定替换操作
    $patchBody = @(
        @{
            op    = 'replace'
            path  = '/variables/aVariableInGroup/value'
            value = 'hello world'
        }
    ) | ConvertTo-Json -Depth 10

    # 发送PATCH请求，指定Content-Type为application/json-patch+json
    $results = Invoke-RestMethod -Uri $uri -Credential $credential -Body $patchBody -Method Patch -ContentType 'application/json-patch+json'
    $results
}

内容的提问来源于stack exchange，提问作者Rod